1. INTRODUCTION
Traditionally, geographic information has been produced and used by the geo-spatial community, i.e. experts in specialized fields like geography, cartography, geodesy, photogrammetry, remote sensing, bathymetry, hydrography, geology, soils, physical planning, architecture, etc. The work of these experts resulted in combinations of different geo-spatial datasets in various scales, projections and co-ordinate systems, content and appearance. To make the geographic information available to users, the geospatial community prepares and fulfils measures to develop and implement conceptual and methodological bases, normative and legislative regulations and dataset descriptive standards including formats for spatial data interchange. It also develops implementation methods, hard- and software tools and technologies for acquisition and the transfer of datasets to users, storage, analysis and processing digital cartographic data and the creation of analogue and digital representations of these datasets (Moellering, 1991).
In daily life, public is accustomed to product labels which provide them with information about the products they acquire. These labels have several functions: they identify the product as well as promote it and describe it. In addition, this information is widely controlled by international regulations included in legislation. For geographic data, no such legislation or internationally controlled systems exist. However, now when the geographic community enters the age of global spatial data infrastructures it seems necessary to create internationally controlled systems. Otherwise there is a threat that data may lose their value. Descriptions of geographic datasets have been in existence for some time now. In many cases geographic dataset descriptions for different information communities on regional and national levels evolved in different ways and are incompatible.
Concurrently, there are two main initiatives to solve global interoperability - International Organisation for Standardisation (ISO; http://www.iso.org) and Dublin Core Metadata Initiative (DCMI; Dublin Ohio, The United States of America, see http://www.xml.com/pub/2000/10/ 25/dublincore) as the prominent metadata initiative in the field of Information Technology (IT). The word “metadata” stems from Greek and can be described as “data about data”.
For the first time it was used in Computer science literature in 1968 (Moellering et al., 2005). Although we usually talk about data description, metadata can be used either as a description of a service.
2. ISO 19115
The standard ISO 19115 has been prepared for the description of spatial data by Technical Committee ISO/ TC 211, Geographic information/Geomatics. It relies on the fact that it will substitute currently used standards: FGDC (USA), ANZLIC (Australia), CEN (EU). Nowadays, software producers gradually implement this standard instead of their above mentioned predecessors. Furthermore, current activities in the European Union (EU) in the field of spatial infrastructures (INSPIRE; The Infrastructure for Spatial Information in Europe) are closely associated with this standard as the basis for the description of spatial data. Preliminary CEN standards have been abandoned in the Czech Republic and ISO 19115 has been translated and declared as the Czech national standard (CSN). The work continues with the translation of other ISO 191xx series standards.
This standard (ISO 19115) has been inspired by other metadata standards; however, it is considerably wider (see Table 1) and tries to implement a number of “CodeLists” to prevent addition of free text. All these advantages should lead to the unification of entities implementation. However ,there are a lot of entities that have to be fulfilled manually with free text . This standard has been created with regard to other standards of ISO 191xx series.
Table 1 – Metadata entities in standard ISO 19115.
3. METADATA EXTENSIONS AND PROFILES
The definitions and domain values are intended to be sufficiently generic to satisfy the metadata needs of various disciplines. However, the very diversity of data means that generic metadata may not accommodate all applications. Thus, metadata standards are usually extensible. One component of the standard is a description how to make an extension or community profile – it contains CORE elements and other explicitly defined elements that are dependent on the purpose of the extension or community profile.
Figure 1 – Metadata community profile.
Rules for profile creation are simple. Before creating a profile, the user shall check registered profiles. Then a profile must adhere to the rules for defining an extension – above all it shall include core, optional and mandatory elements. A new element of the extension shall be created only if there are not any appropriate elements in the basic standard. All rules for creating a profile are described in standard ISO 19106. Figure 1 shows the relationship between core metadata components (which shall be always complete), comprehensive metadata profile (which is a part of the basic standard or it is a part of existing extension) and created community profile. There is a part of extended metadata highlighted with grey color in the Figure 1 – only these are the new metadata elements.
4. METADATA IN ESRI PRODUCTS
The main product for metadata creation, editing and maintenance is ArcGIS. ArcCatalog (see Figure 2) brings . key functionality from all components of ArcGIS (ArcMap, ArcCatalog, ArcToolbox, ArcEditor, ArcGlobe and ArcScene). Metadata are in ArcGIS supported natively in the ESRI Profile, which is the community profile generated from FGDC metadata standard. All necessary information about this ESRI Profile is at http://www.esri.com/metadata/ esriprof80.htmlhttp://support.esri.com/).
Export of the metadata can be into the HTML document – then the appearance is exactly the same as in ArcCatalog. However, there are also another export standards, such as FGDC ESRI, FGDC, FGDC Classic, FGDC FAQ, FGDC Geography Network, ISO 19115, ISO Geography Network, XML and text.
There are following disadvantages while using ArcGIS Desktop for metadata creation, viewing and maintenance: Functionality of ArcCatalog is not sufficient in number of cases and that is the reason why another metadata editor has to be also used. Above all, these cases are when metadata for whole directory or geodatabase are created, metadata records are edited or records in the database itself are changed.
According to the ESRI metadata declaration from 2006 (see http://www.esri.com), corrected metadata directory support in version 9.2 should be integrated.
Automatic metadata conversion into the standard ISO 19115 is not fully resolved.
Figure 2 – ArcCatalog (main ESRI metadata application).
Figure 3 – INTERGRAPH GeoMedia Catalog Editor.
Figure 4 – Metainformation catalogue MICKA.
This conversion is correct only to explicitly corresponding entities. There should be changes in ArcCatalog 9.2 too – it should support standard ISO 19139 (Geographic information – Metadata – XML schema implementation).
5. METADATA IN INTERGRAPH PRODUCTS
Intergraph platform contains several useful tools for work with metadata, especially for desktop applications GeoMedia and GeoMedia Professional. Moreover, it provides free metadata editor (Geomedia Catalog Editor– see Figure 3).
As mentioned above, GeoMedia Catalog Editor (GCE; http://www.intergraph.com/geomediacatalog/) is a free available tool for creation of a catalog and metadata records. It creates a spatial metadata catalog and saves specified content into it. It is possible to create, edit, delete and import metadata as well as to export geospatial metadata records as user’s own defined profiles. GCE is a successor of Intergraph product GeoMedia SMMS, which has been designed to the same purpose as GCE.
Almost all relational databases are supported, including the possibility of a database creation for catalogue purposes while using stylesheets for databases Microsoft Access, Microsoft SQL (Structured Query Language) and Oracle. Following export outputs are supported: FGDC Encoded ASCII (*.txt), FGDC Encoded HTML (*.htm), FGDC Encoded XML (*.XML), ISO-19139 Encoded XML (*.xml), GeoMedia Catalog Exchange Format (*.gce). Import of catalogue records is possible only from these exchange formats: SEF (GeoMedia SMMS), GCE, TXT (FGDC) a XML (FGDC).
There is also an administration tool Thesaurus/Keyword for creation of new elements and datasets documentation in a Catalog Editor. This tool can create thesaurus entities that are containing a list of keywords. The end user then can select keywords and thesaurus in the Catalog Editor. Intergraph is going to improve GeoMedia Catalog Editor functionality in the field of queries integration, portrayal and metadata editing and wider support of different standards than FGDC – ISO 19115 and jsome OGC (Open Geospatial Consortium) standards – these are the biggest weaknesses of GCE now.
6. MICKA
MICKA (see Figure 4) is a commercial software of Help Service Remote Sensing (see http://www.bnhelp.cz) written to satisfy user’s need in the Czech Republic.
Nowadays, this software is also available in other countries – supported languages are English and Czech. Main purpose of this tool is the software implementation of metadata standard ISO 19115. Due to the absence of the description dataset structure, a standard for Feature Catalog description, ISO 19110 – a subset of appropriate elements for data structure description, has also been implemented in this software.
Till present, there have been implemented these standards: ISO 19115 (description of spatial data) – full standard, ISO 19119 (Geographic information-services), ISO 19110 (Geographic information – – Methodology for feature cataloguing) – the subset of elements for the basic Features description (attributes, domains) and ISO 15836 (Dublin Core metadata).
Metadata are saved in a relational database – each element has its own record in an attribute table. Other tables have a defined structure of XML elements tree. Thus, it is possible to save any XML document if an appropriate structure in the definition tables is defined. Searching is then enabled with common functionality of SQL. There are two main searching possibilities – fulltext when using some predefined criteria, or spatial queries (when using selection by drawing a rectangle in the map or adding geographic coordinates). Import and export are supported for: ESRI ArcCatalog ISO XML, OGC Web services (WMS and WFS), ISVS standard (former Czech national standard for metadata), ISO 19139 XML, ISO 19115 and ISO 15836.
Data viewing could be done only via software extension because it is not a component of the whole application. The next progress is going to fully implement OGC CS-W and ISO 19139.
7. GEONETWORK
This application is developed under the Food and Agriculture Organization of the United Nations (FAO) for information and data sharing within the framework of UNSDI and other activities. It is Open Source software published under GNU/GPL. There are a lot of installation nodes across the world. These nodes can communicate
together and this fact allows consistent
sharing and searching of metadata and data
(see Figure 5).
Figure 5 – GEONETWORK initial screen.
This application is provided in “light desktop version”, which enables easy creation of user’s own metadata on their personal computer. Current version is 2.0.2. Till now, there have been implemented these standards: ISO 19115 (description of spatial data) – XML FAO Profile, FGDC, ISO 15836 (Dublin Core metadata). A support for standard ISO 19139 is being prepared presently. This software is written in java language as a JSP application. It can use any relational database; desktop version is provided with MCKoi database system, while server version is provided with MySQL. User and service interface are based on XSL stylesheets, that’s why it is possible to create user’s own configuration. Application also provides Web environment for online data creation and editing. Querying page enables searching with free text in the title, abstract, keywords and spatial queries (in the map), etc. The software provides import and export of XML files that are ISO 19115 FAO compliant and batch import of several records. There is an extension that can convert ESRI ArcCatalog data to the Geonetwork understandable format. Furthermore, there are supported catalogue services based on standard Z39.50. The next version should support standard ISO 19139 and implementation of catalogue services OGC CS-W.
8. METIS
METIS (see Figure 6) is a commercial software of T-Mapy that uses ISVS standard (former Czech national standard for metadata description) in the way suitable for public administration institutions. ISVS standard has been extended in this case to legend, pictures and other documents evidence. Current version is METIS 3; the next version should support ISO 19115. The application is written in PHP language and allows using any relational database. Data are saved in the traditional relational database model where objects and possibilities of their connections are defined. Import and export is supported for MIDAS Import, ArcCatalog and ArcSDE. Besides these user can export data also to RTF (Rich Text Format). When using ShellExtract module, a tight integration with Windows Explorer is established. This application is only in the Czech language and does not support any international standard.
Figure 6 – metadata list of METIS.
CONCLUSIONS AND FUTURE WORK
This full paper brings main characteristics of selected GI platforms according to their metadata implementation. Although there is a trend to use world standard ISO 19115, its software support is not at the appropriate level so far. Above all, this is caused by historical conditions. At the beginning of metadata standards, a lot of them had been developed by different institutions or nations. This diversity was useful at the beginning because it also had been a way how to develop new standards or how to add new ideas into newly created standards. Nowadays, these standards have become a relatively homogenous – that is why they have been usually changed only with extensions or community profiles according to the purpose of the use. At the same time, there is a need to integrate metadata. There are some theoretical studies (e.g. Moellering et al., 2005) but functional realization is not yet provided. Thus, automatic conversion of metadata from one standard to another can result in a loss up to 50% of all metadata records.
According to the GI software producers’ declarations, it is possible to say that all of them have implemented or are planning to implement ISO 19115 into their software and thus substitute former FGDC standard. According to the metadata implementation correctness the best-tested GI platform is MICKA. This is the only one software that fully supports both the description of spatial data (ISO 19115) and the description of services (ISO 19119). Furthermore, it implements ISO 19110 to enable full description of spatial data including their data structure. Import and export from / to ArcCatalog and OGC formats are supported correctly. The main disadvantage of this solution, however, is separated data and metadata capture. Still, it is a typical example of how smaller firms answer quicker to the market needs of metadata integration than traditional GI leaders (ESRI, Intergraph). The traditional GI leaders are going to implement ISO 19115 correctly in years 2007 and 2008. Bentley platform has been not analyzed because of the absence of the appropriate Bentley metadata software.
Above-mentioned analysis of selected GI platforms is a basis for future work. It means defining a way how to integrate metadata independently on the used GI platform This is going to be the main activity of the projects during 2007. This research has been supported by funding from the project No. MSM0021622418, called Dynamic geovisualization in risk management, and the project No. T206030407, called Management of geographic information and knowledge.
LITERATURE
[1] ArcCatalog metadata support, http://www.esri.com
[2] ArcGIS 9 – co je noveho?, http://www.arcdata.cz
[3] ArcView 3.x Metadata extension, http://www.esri.com
[4] ESRI Profile of the Content Standard for Digital Geospatial Metadata, http://www.esri.com
[5] Geonetwork, http://www.fao.org/geonetwork/sv/en/ main.home
[6] ISO 19110: Geographic information . Methodology for feature cataloguing
[7] ISO 19115:2003 Geographic information – Metadata
[8] ISO 19119:2005 Geographic information – services
[9] ISO 19139: Geographic information - Metadata - XML schema implementation
[10] ISO19115 / ISO19119 Application Profile for CSW 2.0. https://portal.opengeospatial.org/files/?artifact_id=6495
[11] Lucene, http://lucene.apache.org/
[12] Mapping between Dublin Core and the ISO standard 19115, “Geographic information - metadata”, draft version, CEN/ISSS Workshop Metadata for Multimedia Information
– Dublin Core, April 2003
[13] Metadata and GIS, http://www.esri.com
[14] Metadata Support in ESRI products, http:// www.esri.com
[15] METIS, http://www.tmapy.cz/public/tmapy/cz/ _aktualne/_novinky/_novinky_2006/ metis_new.html
[16] Micka, http://www.bnhelp.cz/bnhelp/micka.htm
[17] MIDAS, CAGI metainformation system. http:// www.cagi.cz/midas
[18] MOELLERING, H.: World spatial metadata standards. International Cartographic association. Elsevier Ltd., London 2005. ISBN 0-08-043949-7.
[19] MOELLERING, H: Spatial database transfer standards: current international status. International Cartographic Association. Elsevier Applied Science, London 1991. ISBN 185166677X.
[20] Open geospatial consortium: OpenGIS® Catalogue Services Specification 2.0 [21] Standard ISVS pro strukturu a vymenny format metadat informacnich zdroju - 011/01.02. Ministerstvo informatiky CR, http://www.micr.cz/files/470/ uvis-S011.01.02-20020222.pdf
Rules for profile creation are simple. Before creating a profile, the user shall check registered profiles. Then a profile must adhere to the rules for defining an extension – above all it shall include core, optional and mandatory elements. A new element of the extension shall be created only if there are not any appropriate elements in the basic standard. All rules for creating a profile are described in standard ISO 19106. Figure 1 shows the relationship between core metadata components (which shall be always complete), comprehensive metadata profile (which is a part of the basic standard or it is a part of existing extension) and created community profile. There is a part of extended metadata highlighted with grey color in the Figure 1 – only these are the new metadata elements.
Anónimo